This application will automatically figure out which data type to return,
using a combination of user agent parameters and URL extensions. If a user
agent requests “/test.html” they will get HTML, but if they request
“/test.json” they will get JSON instead. No longer do you have to worry about
constructing sites with separate interfaces for HTML and JSON; one holstered
site can do it all!

Holster currently has default renderers for the following formats:

HTML

JSON

Plaintext

YAML

Users can also override renderers for any format or MIME type they would like,
with with_template: